134 THE MYXOMYCETES. 



granted that they are cells, contain no spiral, the appearance being an 

 optical effect produced merely by a rounded spirally-aiTanged eleva- 

 tion of the outer wall.* The spores also outwardly are like the spores 

 of many other Fungi, but the development of the spore is sui peneris, 

 and its contents, as soon as they have developed their fiagellum, 

 resemble common free-swimming monads, and in their creeping stage, 

 first, the infusorian Mastigamoeba, and, secondly, the rhizopod Amceba. 

 Again, we can compare the huge plasmodium formed by their union 

 with the ramifications of the protruded protoplasm of the Foramini- 

 f era, in which also the same cyclosis or slow circulation of the contents 

 is observed. It may also be compared, according to Saville Kent, to 

 the homogeneous sarcode which forms the basis of sponge structure, 

 which in the same way is composed, if our authority be correct, by 

 the amalgamation of a vast number of amcebiform units. Moreover, 

 the substance of the threads which occur with the spores, according 

 to the same author, bears some likeness to that of the keratose or 

 horny fibres of the order of Sponges called Ceratina, while still more 

 strangely the calcareous deposits in many species simulate those of 

 the order of Sponges called Calcarea, and in a few, he says, even 

 assume a regular six-rayed form, reminding one irresistibly of a sponge 

 spicule. But in these respects the author's enthusiasm seem to have 

 outrun his judgment ; the threads of the Myxomycetes are not of a 

 very homy nature, nor are the crystals by any means so regular as he 

 would imply. 



But, even allowing these resemblances, and that the Sponges 

 belong to the Protozoa, can we find anything in the Protozoa at all 

 comparable to the last spore-bearing stage of the Myxomycetes ? 

 Saville Kent answers in the affirmative, and compares it with the 

 encystment of species of Monas and Heteromita, such as has been 

 revealed by the labours of Messrs. Dallinger and Drysdale, a process 

 similar to which, according to Saville Kent's own observations, is very 

 prevalent among the Protozoa, although unknown a few years ago. 

 The chief difference is one of degree, the sporangium in the Myxomy- 

 cete being formed by the union of a vast number of amcebiform units, 

 and in the Protozoan usually by the combination of a few only. But 

 this difference is bridged over bj' those species with aggregated plasmo- 

 dium, described by M. Van Tieghem (supposing them to belong really 

 to the Myxomycetes), where the sporangium is formed at times by a 

 small number of myxamoebae only.f 



The only real distinction^ between the Animal and the Vegetable 

 Kingdoms (if there be one at all) is founded upon their physiology. 

 Plants possess the power of building up organised substances out of 

 dead matter ; animals require ready organised material for their food. 

 Fungi, indeed, resemble animals in this respect, that they usually live 



* " Quarterly Journal of Microscopical Science," 1855, pp. 15-21. But the 

 opposite opinion has been maintained ; " Transactions of the Linnsean Society," 

 sxi., pp. 221-3, wliere, however, the fifiure contradicts the text. 



t Van Tieghem, •' Bull. Soc. Bot. France," xxvii., pp. 317-22. 



t Huxley's " Science and Culture," p. 162. 



